1. Field of the Invention
The present invention relates to an inflatable cushion assembly for use in an inflatable restraint system, and in particular to an assembly, system and method for coupling an inflatable cushion to a reaction housing in an inflatable restraint system.
2. The Related Art
Inflator restraint systems generally include an inflatable cushion (commonly referred to as an air bag), an "inflator" for providing gas to inflate and deploy the cushion upon sudden deceleration of a vehicle employing the restraint system, and a reaction housing or canister for supporting and/or containing the air bag and inflator. In such systems, commonly referred to as an air bag module, the cushion typically has an open section that defines a gas inlet opening for receiving the gas upon activation of the inflator. Because of the great amount of force exerted on the cushion and reaction housing during the initial stage of inflator activation, the coupling and securement of the cushion to the canister becomes important, if not crucial, for proper functioning of the cushion during its deployment. In assembling the module, it is important to couple the cushion with the reaction housing in a manner that is simple and economical, and yet which will provide a secure and reliable attachment.
One such system for attaching an inflatable cushion to a reaction housing is disclosed in copending application Ser. No. 07/993,280, filed Dec. 18, 1992 by Lauritzen et al., now allowed, U.S. Pat. No. 5,344,182 issued Sep. 6, 1994 which is assigned to the assignee of the present invention and is incorporated herein by reference in its entirety. The system employs a metal cushion retainer which includes a pair of cylindrical channel portions that are separated by spacers (FIG. 4) into which a corresponding pair of thickened peripheral gas inlet openings of an inflatable cushion is inserted (see FIG. 3). The thickened gas inlet opening is typically formed by hemming the gas inlet opening of the cushion to form a channel into which a bead material, such as a plastic rod, is inserted. Once formed, the thickened gas inlet opening is inserted into the respective channel portion of the cushion retainer to define an attachment insert (FIG. 4) which in turn is incorporated into an attachment sleeve of a reaction housing for the fastenerless attachment of the inflatable cushion thereto.
While the use of a plastic rod in the hem of the gas inlet opening of the cushion facilitates the equal distribution of stresses on the cushion during its deployment, as well as to assist in the avoidance of point loading of those stresses, the bead material or rod will have a tendency to fall out of its channel or hem both during the handling of the cushion and during its assembly into the inflatable restraint system. Moreover, if the stresses imposed on the cushion during its deployment are in excess of operating standards, the bead material or plastic rod will have a tendency to pop out of its respective containment if it is not properly seated or retained in the cushion retainer, thereby causing a failure of the attachment arrangement for joining the cushion to the reaction housing. Additionally, the material of the thickened gas inlet opening is subjected to rupture or tearing when it is being assembled to the metal cushion retainer which causes the assembly process to be a cumbersome operation.
Systems utilizing some form of insert positioned in a channel formed at the mouth of an inflatable cushion are known in the prior art. In U.S. Pat. No. 4,817,828 issued Apr. 4, 1989 to Goetz, a metal bar is inserted into a pocket formed by overlapping the material of the airbag and sewing a hem or stitch line (FIG. 21). Both the airbag material and bar are connected with the edge of a canister by a staple inserted through the canister, airbag fabric and metal bar, thereby necessitating the additional use of human intervention for the alignment process, and also for the installation of the staple during the airbag's attachment assembly process. The same holds true with the arrangement illustrated in FIG. 2 wherein the strip, airbag material and reaction canister sidewall are crimped to form a toggle lock. In each case, the fabric of the air bag is exposed to tearing during the assembly process.
In another arrangement, a clamping means is used to connect an inflatable bag to the housing of an automotive restraining device as disclosed in U.S. Pat. No. 4,111,457 issued Sep. 5, 1978 to Kob et al. The gas inlet portion of an air bag is bent about a cord-like insert to form a bead shaped rim for its introduction into a key-shaped channel of a profiled strip (FIG. 2). The profiled strip, which is made of a rubber-elastic material, is designed for circumferential engagement with a continuous flange provided about the peripheral end of the housing. Once the profiled strip is mounted to the housing, a ring, consisting of two halves (FIG. 1), is clamped about the rim-containing strip to engage the inflatable bag with the housing flange. The assembly process for this arrangement requires a continuous cord-like material circumferentially mounted to the housing for attachment of the air bag.
A system utilizing two segments of a U-shaped mounting rod inserted into two hem loops of an air bag for securing the hem loops to an inflator housing container is disclosed in U.S. Pat. No. 5,263,739 issued Nov. 23, 1993 to Webber et al. The hem loops are retained on the common mounting rod (retainer 20) by the attachment of a plate to the ends of the two rod segments with a pair of push nuts (see FIG. 1). Unfortunately, the hem loops of the air bag must be placed into the grooves of chute flanges before the hem loops can receive the rod segments therein, thus making the air bag attachment a difficult and time-consuming process.
Other systems utilizing an insert in a channel formed at the mouth of an inflatable cushion are described in
U.S. Pat. No. 3,514,125 issued May 26, 1970 to Nemecek; PA0 U.S. Pat. No. 4,941,678 issued Jul. 17, 1990 to Lauritzen et al.; PA0 U.S. Pat. No. 4,986,569 issued Jan. 22, 1991 to Bruton; PA0 U.S. Pat. No. 4,988,119 issued Jan. 29, 1991 to Hartmeyer; PA0 U.S. Pat. No. 5,069,480 issued Dec. 3, 1991 to Good; PA0 U.S. Pat. No. 5,186,492 issued Feb. 16, 1993 to Wright et al.; PA0 U.S. Pat. No. 5,195,775 issued Mar. 23, 1993 to Komerska et al.; and PA0 U.S. Pat. No. 5,277,442 issued Jan. 11, 1994 to Cuevas;
Unfortunately, such arrangements typically employ fasteners, such as rivets, bolts, screws, staples and the like, to secure the cushion in one form or another to an associated member of the inflatable restraint system. Moreover, none of the systems described in the above patents addresses the need for retaining the inserts in the pocket or channel of the cushion to provide for an improved fastenerless coupling of the cushion to an associated member of the inflatable restraint system.